


flames and cinders

by Ellidappler



Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Alpha Sylvain, Alpha/Alpha Relationship, Alpha/Beta/Omega Dynamics, Angst, Blood, Character Death, Intercrural Sex, M/M, Mating Bond, Rutting, Thighfucking, This is not a happy fic., Vomiting, alpha felix, no beta we die like men
Language: English
Status: Completed
Published: 2019-10-16
Updated: 2019-10-16
Packaged: 2020-12-31 02:29:04
Rating: Mature
Warnings: Major Character Death
Chapters: 1
Words: 3,688
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21049958
Author URL: https://archiveofourown.org/users/Ellidappler/pseuds/Ellidappler
Summary: “Felix, you’re presenting. You’re going into rut. You need to get out of here.”Felix huffs and rolls his eyes. “No, I’m a beta. I’m too old to present. My hormones have just been acting up and I’ve been a bit more fragrant these days is all.”A very belated Day 1 fill for Sylvix Week. Prompt: Promises.This is NOT a happy fic.





	flames and cinders

The low evening light isn’t the best for sparring. Sylvain’s attacks are missing more often and his form is growing sloppier. Felix isn’t doing much better, his usually monstrous stamina nowhere to be found today. He’s drenched in sweat, his bangs plastered to his face and cheeks flushed. The swordsman has been stumbling more than usual, and as they finish up their latest round of sparring, Sylvain notes that Felix looks like he’s going to faint any second now.

“Hey,” he whines, making a show of placing one end of his wooden lance on the ground and leaning on it, looking like a portrait of exhaustion. Sylvain may be exaggerating it, but he truly is tired. “You’ve beaten me enough times. C’mon, let’s get cleaned up and grab something at the dining hall before it closes.” Sylvain is careful to phrase it like _he’s_ the one in dire need of a break, knowing that asking outright about Felix’s wellbeing would only make the other defensive.

To his surprise, Felix doesn’t scold him for wanting to quit too soon or insist on training more alone. He simply nods, moving to return his training sword to the rack. Sylvain follows suit, returning the wooden lance to its place and moves to drag Felix to the bathhouse before he can change his mind about training. When he grabs Felix’s hand, the swordsman grumbles that he is not a child, his face red with irritation and lingering exertion, but he does not slap it away like he normally does. His hand is sweaty and slick and gross against Sylvain’s own clammy grip, and though the feeling should be entirely disgusting, Sylvain relishes it instead. He can’t have Felix. He knows this. One day Sylvain will be made to mate with someone he cares nothing for and forced to sire pups until one comes out bearing a Crest. Felix is a beta. As much as Felix churns up Sylvain’s heart and dominates his thoughts, he will never be the someone he gets to spend the rest of his life with.

So he’ll just take Felix’s hand now, damp and disgusting, and imprint the feeling in his memory.

When they reach the bathhouse, Sylvain reluctantly lets go of Felix’s hand so they can change. They both begin to strip so they can get in the baths, and Sylvain is halfway through shimmying out of his pants when the scent of an alpha entering rut assaults his nose and he growls.

Sylvain whips his head around to find the scent’s source, a snarl on his lips, offended that someone so close to rut would dare come to stink up the bathhouse. Only he and Felix are in the room. Felix is staring Sylvain down and biting his lower lip, enraged, looking one moment away from growling back. He’s peeling off scent blocking patches from his scent glands, one halfway off of his neck. Felix blinks and the defensive expression disappears from his face, and Sylvain can only gape as everything clicks into place.

The alpha intruder is Felix. His scent was difficult to recognize at first, as it is much deeper and more complex than usual, smoky like firewood crackling within flames and spicy like gingerbread. It’s unmistakably Felix, though, the refreshing undercurrent of pine the same.

“Felix, you’re presenting. You’re going into rut. You need to get out of here.”

Felix huffs and rolls his eyes. “No, I’m a beta. I’m too old to present. My hormones have just been acting up and I’ve been a bit more fragrant these days is all.”

“_No,_” Sylvain says trying not to come across as too aggressive so that Felix’s budding alpha doesn’t feel threatened. “You’re definitely presenting. Have you been feeling like you’re in a fog, like the world is too full of sensations, that everyone is suddenly either a threat or a friend who needs protected?”

Felix’s lips twitch in irritation and he doesn’t respond. It’s all the answer Sylvain needs.

“I’m going to leave so you can get cleaned up. I’ll watch the door to the bathhouse so no one can disturb you, then walk you back to your room. Okay?”

Felix only scowls and turns heel, which is about as good an answer as Sylvain is going to get. Sylvain quickly redresses and goes to watch the door to the bathhouse, as he had promised. After ten minutes, Felix stumbles out, showered, in a fresh uniform, and looking in a daze. The scent of rut is growing thicker, heavier, and Sylvain knows he needs to get Felix back to his room _now._

“I’m going to grab your wrist, okay?” Sylvain warns, gently taking Felix’s hand in his. Felix snarls and lunges, looking ready to chew Sylvain’s face off, until he realizes at the last moment who it is and relaxes. Sylvain only chuckles nervously in response and begins guiding Felix back to his room, thankful that Felix recognizes him as an ally and does not resist. He shifts every time they pass by an omega en route, turning to glare and seeming as if he’s contemplating chasing down the poor thing, but a gentle squeeze from Sylvain brings him back to his senses each time.

They get back to Felix’s room and Sylvain practically shoves him inside it, closing the door behind him. “Okay, you stay here. You’ll from Manuela and some food from the dining hall, so I’ll go grab it f-“

Felix cuts him off with a growl, low and dark, eyes dying embers. “Stay.”

Sylvain is unfazed by the growling and moves to open the door so he can leave. Felix tackles Sylvain to the ground and pins him down, legs straddling Sylvain’s chest, bent over so that he’s growling right in Sylvain’s face.

“_Stay._”

Sylvain can feel his heart throbbing in his throat. Felix’s bangs, still damp from his bath, are brushing against his forehead, and though he looks one second away from ripping Sylvain’s throat out with his teeth, his expression is tinged with fear, as if he does not trust himself to be alone. His usual facade of stoicism and aggression is cracking, revealing a level of vulnerability Sylvain hasn’t seen in years.

“Yes,” Sylvain agrees, and Felix immediately relaxes. The swordsman stands and helps Sylvain to his feet, then looks nervously toward the bed.

“Could we- cuddle? Would it be alright if I scented you?”

Sylvain nods, and they settle down on the bed, Felix spooning him. He presses his against the scent gland in the crook between Sylvain’s shoulder and neck, breathing deeply, taking comfort in the familiar scent. Sylvain tries not to think about how intimate the act is, how, in a different life, one where they are biologically compatible, Felix would lick the mating gland just a few inches away on his neck to arousal, then bite down, binding them together forever. Sylvain tries not to think of a universe in which they can be together.

Sylvain fails. It feels like his heart is being ripped out of his chest.

Oblivious to Sylvain’s dilemma, Felix hooks his ankle around Sylvain’s legs, pinning him in place, trying to get more comfortable. He shifts again a few moments later. Nearly a minute passes, and then he moves again. Sylvain feels something firm poking against his backside and realizes that Felix is attempting to refrain from humping him and and struggling.

It’s a shocking realization. Sylvain was under the impression that Felix was wanting him here as a platonic source of comfort, as a member of his pack, not a potential partner. It shouldn’t send a little thrill of excitement down Sylvain’s spine. Sylvain is an idiot for hesitating to stop things before they go too far, before sampling what he can’t have. He’s a starving man being offered a taste of the gods’ ambrosia, and he’ll be ruined for life if he doesn’t stop here.

Felix nuzzles the scent gland near Sylvain’s collarbone and he shivers, all reason flying out the window. He twists his neck to look at Felix.

“You’re hard.” Felix’s face flushes in embarrassment and he begins to stammer out a response, but Sylvain cuts him off. “You want help with that?”

After a long moment, Felix nods his assent. Sylvain wriggles out from his grasp and stands, peeling off his clothing. Felix is looking at him approvingly, eyes raking over his form and glinting with arousal. “Should I take off my clothes as well?”

“That would be optimal,” Sylvain responds. “Do you have sword oil somewhere?”

Felix gestures towards a bottle on his desk and Sylvain grabs it while Felix strips. Felix takes off his boots first, and Sylvain eyes them while he waits, wondering if he dares to ask.

Well, this is the only chance he’s going to get. He may as well seize it.

“Would you mind putting your boots back on?”

Felix’s lips curl in amusement. “Why?”

“They look nice on you, and- listen, just do it, please.”

Felix obliges, slowly pulling them on, making a show of it as the leather slides over his toned calves and hugs his muscled thighs. Between his legs, Felix’s cock is flushed with arousal, and Sylvain feels almost dizzy with anticipation.

Sylvain lays down on the bed so that he’s on his back. Uncorking the bottle of sword oil, he coats the inside of his thighs with it until they glisten in the low light. Sylvain’s slept around with all sorts of people, from alpha to omega, and while he’s bottomed for an alpha male before, he hasn’t taken a knot yet. While Felix is normally quite reliable, rut does strange thing’s to someone’s impulse control, and Sylvain doesn’t quite trust a rutting Felix not to break him on his knot. He’ll have to hope that thighfucking will be enough to satisfy him.

It comes as a slight surprise when Felix clambers on the bed and flips Sylvain over, then positions the redhead so that he’s on his hands and knees, ass in the air and thighs pressed together. Sylvain never would have expected for Felix to have picked up so easily on what he had in mind, to be so confident in bed, to seem so... experienced. The thought that Felix may have done something similar with someone else makes jealousy curl in the pit of Sylvain’s stomach. It’s unfair, he knows, given how much Sylvain sleeps around, and the hypocrisy makes him feel disgusting.

He doesn’t get much time to think, though, because soon Felix is thrusting forward, his cock sliding between Sylvain’s thighs and against Sylvain’s balls, and _oh_, the drag of skin against slick skin is intoxicating. A breathy moan escapes Sylvain’s lips. Felix leans over to nip and nibble at the junction of Sylvain’s neck and shoulder, and Sylvain can feel his hot, ragged breath against his skin. The snap of Felix’s hips is harsh and unforgiving, the rutting alpha chasing his own release, any pleasure he gives to Sylvain simply a fortunate byproduct. Sylvain knows that he ought to feel ashamed to be used by another alpha like this, to so easily and gladly submit, but he can only groan at how right and perfect everything is. Felix’s arms are wrapped around his waist, his chest flush against Sylvain’s back, and the redhead knows that he can now die and say he’s lived a complete life.

The press of Felix’s hips against Sylvain’s is growing erratic, a sign that he’s close to climax. When Felix suddenly stops, Sylvain expects to feel semen coat the inside of his thighs. Instead, Felix murmurs in his ear in an incredulous tone, “Your mating gland is aroused.”

Sylvain slaps his hand over his neck and scrambles away, getting as far away from Felix on the bed as he can. The swordsman is staring him down with an unreadable expression, the emotions he’s feeling too mixed up for his face to convey.

“Sylvain,” Felix begins, and Sylvain laughs. The sound is obviously fake, forced, and Felix’s lips tug into a frown.

“Ahahahaha, this is so awkward. Mating glands act up during sex, you know, there’s no helping it-“

“Sylvain. We both know that’s not how they work.”

He swallows, mind racing as he tries to find a way to wriggle his way out of this predicament. Felix is looking at him with hurt on his face, as if he’s some sort of monster. Sylvain wouldn’t blame him if he thinks that. He’s betrayed their friendship and Felix’s trust by going and falling in love with him.

“I mean, it’s rare, but...”

“No. They only get aroused when someone wants to mate, when they decide that they want to be with someone for life.”

“That’s-“

Felix lunges forward before Sylvain can finish voicing his paltry defense, and he winces, sure that Felix is about to punch him in the face. Instead, he grabs Sylvain by the wrist and drags his hand so that it rests on the back of Felix’s neck. The skin feels oddly swollen and puffy and damp. Sylvain’s eyebrows furrow in confusion, then shoot up when Felix tilts his head so that Sylvain can get a better look.

Felix’s mating gland is aroused, flushed as red as Felix’s scarlet cheeks. Sylvain’s world shatters and realigns in a single moment as everything clicks into place.

“You too.”

“Yes.”

“For how long?” Sylvain asks.

“Quite a few years, now.”

Sylvain bitterly laughs. “God, we’re such idiots, aren’t we.”

Felix ignores the comment, instead rubbing Sylvain’s mating gland with the pad of his thumb, teasing the sensitive skin. “What are you going to do about it?”

Sylvain shudders, barely able to form a coherent thought, never mind a response. “I, uh-“

There’s a brush of something against his mouth, and his vision goes black. _No,_Sylvain realizes. He’s looking at Felix’s hair, the silky strands pressed against his nose, his swollen mating gland flush against Sylvain’s lips. If someone could make an incubus into a candle, Sylvain is pretty sure it would smell like Felix does now, like cloves and pine needles and desire and cries of _take me, I’m yours._

“Bite me, you coward,” Felix growls, and almost immediately Sylvain feels soft skin break beneath his teeth and tastes blood as it fills his mouth. Felix is trembling, body taut and eyes glazed over with pleasure, his cock spurting its release onto the bedsheets. Sylvain laps at the droplets of blood from the fresh mating bond until Felix melts into his arms. He presses a few kisses into the top of Felix’s head until Felix regains his bearings and sits up.

There’s a look of pure adoration in Felix’s eyes, as if Sylvain is the most incredible person in the world. Sylvain feels his throat grow dry. Felix hasn’t looked at him since they were kids, when Felix would get awestruck every time Sylvain showed off and act as if Sylvain could lasso the stars. Sylvain’s chest feels tight, warm, unbearably full, as if it’s going to burst open any second now.

“My turn,” Felix murmurs. He leans forward and gently tilts Sylvain’s head so that the back of his neck is better exposed. Teeth sink into supple flesh, and Sylvain jerks in Felix’s grip, his eyes fluttering closed. Splotches of color bloom and dance behind his eyelids and he feels as if he’s floating. The worries of the world fade away, and Sylvain is convinced that he’s being pulled towards the heavens. The only thing tethering him to this plane of existence are Felix’s arms wrapped around his midriff.

When Sylvain comes down from his high, his lap is covered in semen and Felix is intently staring at him, his eyes filled with concern and fondness. The swordsman perks up when Sylvain turns to look at him and scoops him up so they’re spooning again. Exhausted and content, he drifts off to sleep, Felix’s nose buried in his hair. Maybe he’s imagining it, but he swears that he can feel Felix’s lips form a smile as they press against his scalp.

* * *

It doesn’t take word of their mating much time to get around. The general reaction of the students and staff of the monastery is a relieved _finally,_ although Sylvain’s father is significantly less pleased to learn of it. Sylvain is promptly disowned and declared a disappointment and disgrace. Duke Fraldarius, to his credit, seems supportive of the arrangement. One of Felix’s baby cousins bearing the Fraldarius crest is named to be the successor to the dukedom following Felix.

Shortly after their mating, the war breaks out. Sylvain and Felix work to protect the Fraldarius lands, and eventually to defeat Edelgard’s Imperial forces. Margrave Gautier reportedly has some regrets about disavowing his militarily trained son as he struggles against the Sreng, but never sends Sylvain so much as a letter. Sylvain is fine with this. Felix is by his side and he needs nothing else.

The pair of alphas are a menace on the battlefield, working together in perfect synchronization and leaving a trail of bodies in their wake. Together, they seem to be a force of nature, as powerful and unstoppable as a hurricane.

But they aren’t unstoppable.

One day in battle, their forces become overwhelmed. They’d been fighting for days on end with no rest, and with adrenaline having worn off, both sides are exhausted and fighting sloppily. Even Felix, with his monstrous stamina, is running on sheer willpower at this point, his sweat gleaming in the low evening light as he tries to push back the enemy troops.

Exhaustion bests Felix. An enemy cavalryman storms Felix just as the swordsman finishes dispatching a mage and pierces him clean through. The lance goes through his back and out his chest, and he dangles from it like a piece of meat on a skewer.

Felix looks down at his chest and then up at Sylvain, regret glimmering in his amber eyes. “I’m sorry,” he says. The next words are merely mouthed, the gush of blood spewing from his lips silencing any sound.

_I love you._

The cavalryman flicks Felix’s corpse off of his lance with disdain, then turns his attention to Sylvain. He’s a moment too late. The redhead is already hacking at the cavalryman with his lance, continuing to slash and stab long after he has fallen. When Sylvain finally exhausts himself, he falls to his knees next to Felix’s cooling body. Felix’s eyes are glassy and lifeless, as still and beautiful as honey-colored marbles. Blood dribbles down his chin and Sylvain cups his cheek, a guttural scream ripping from his throat as he cradles the face of his fallen lover. His sobbing is animalistic, inhuman. Snot pours from Sylvain’s nose and tears blur his vision, obscuring the horrible sight of Felix’s lifeless gaze.

Hours later, after the battle has finished, the rest of the Blue Lions manage to coax Sylvain away from the battlefield and Felix’s body. Apparently Dedue and Ashe had spent the rest of the battle guarding the grieving Sylvain, fending off enemies that decide that the inconsolable Sylvain would make for an easy target.

Sylvain doesn’t say it, but he wishes that they had let him be killed.

Felix is buried in Fraldarius territory. The funeral, as far as funerals for nobility go, is simple and relatively free of fanfare.

In the following weeks, Byleth sends Sylvain into battle less and less often. This is for good reason: he fights like a man with nothing to lose, because that’s exactly what he is. He’ll get himself killed if deployed, and so Byleth wisely benched him.

At meals, he eats less and less. What little he manages to stomach is vomited up, more often than not. Sylvain sleeps little, spending most nights staring emptily at the crackling branches of campfires. He’ll spend hours inhaling the smoke of the burning pine logs, the aroma reminding him of Felix. When the fire dies down to embers, he is reminded of Felix’s eyes. The cinders become ashes and Sylvain hollowly stares at them, thinking of how Felix, now, is little more than ashes.

The Blue Lions’ concern slowly grows. They begin to whisper about bond death, about how sometimes, when one half of a mated pair dies, the other will follow in extreme grief. They try to intervene. Mercedes persuades him to eat, Ashe starts giving him herbs to help him sleep, Annette comes to him to attempt to cheer him up with stories and silly songs. Despite their efforts, Sylvain continues to waste away. Dimitri at his worst was a paragon of health in comparison to Sylvain in his current state.

In desperation, Byleth tries to find Sylvain another mate. Omegan women come to his bed, guiding his hands to their breasts and trying to seduce him, but he throws them out each time. Alphas and betas with black hair and brown eyes keep making their way to his room, each slightly resembling Felix but never quite as lovely. No one could ever be.

One day, Sylvain simply doesn’t wake up. Dedue goes to fetch him for breakfast and finds that he has passed in his sleep, curled up in his bed and clutching a miniature portrait of Felix. Bond death had taken him, despite their best efforts to save him.

Sylvain is buried next to Felix. The funeral itself was a private, simple affair, but in centuries to come, countless poets and novelists would write about it, depicting Felix and Sylvain’s deaths as a great romantic tragedy. Their love became immortalized in paintings and movies. They would become a symbol for the same-dynamic couples’ movement. The depth of their bond and love for each other was so deep that time failed to erase memory of it, and they were immortalized, at least in remembrance. In actuality, they lay side by side under the dark earth, one coffin brushing the other, as if in a kiss.

* * *

_Do you remember the promise we made when we were kids? About sticking together until we died together?_

_I remember._

_I meant it. I’m a man of my word, Felix._

**Author's Note:**

> lemme know if you find any typos/errors and feed me comments, please


End file.
